Means for drawing off blast furnace gases by suction in roasting, calcining, and drying furnaces



J. HQRAK 2,186,675 MEANS FOR DRAWING OFF BLAST FURNACE GASES BY SUCTION Jan. 9, 1940.

IN ROASTING, CALCINING, AND DRYING FURNACES Filed Feb. 4, 1939 Patented Jan. 9, 1940 MEANS FOR DRAWING OFF BLAST FURNACE GASES BY SUCTION IN ROASTING, GAL- CINING, AND DRYING FURNACES Josef Horak, Eisenerz, Germany Application February 4, 1939, Serial No. 254,735

In Austria February 19, 1938 2 Claims. In order to enable the material that is to be charged, in roasting and calcining furnaces that require an open top, to be brought in and distributed without being hindered by waste gases and dust, according to this invention a-suction grate is arranged immediately underneath the open top of the furnace. This suction grate consists of hollow bearers, which are located side by side with spaces between them, and which are provided with suction apertures, with their open ends opening into suction passages leading.

to a ventilator or to the chimney stack or the like. This renders unnecessary the known superstructures upon the top of the furnace shaft, such Figures 1 to 3 represent a rectangular shaft furnace, and

Figures 4 to 6 a round shaft furnace, without and with dust-removing'nozzles.

Figures 1, 4 and 7 are sectional elevations taken transversely through the hollow grate-bar bearers;

allel to the hollow grate-bar bearers, and Figures 3 and 6 are plan views.

Transversely above the furnace shaft at dishollow grate-bar bearers l. The charge need only reach up to the upper edge of the suction grate, in the case of an ordinary size of grain, in order to prevent the suction of secondary air under side of the hollow grate-barbea'rers I.

In order to enable as many hollow grate-bar bearers l as possible to be located in the cross section of the furnace, and to prevent anyappreciable segregation of the charge, the hollow gratebar bearers I are made narrow, and preferably exhibit a rectangular cross section standing on edge, which is saddle-shaped at the top.

ers I open according to Figures 1, 2 and 3 into Figures 2 and 5 are sectional elevations partances that are determined according to the size of grain of the material to be treated run tubular through'the suction aperturesi provided on the v The open ends of the hollow grate-bar bearpassage 7, which increases in depth from the mouths of the middle hollow grate-bar bearer on both sides towards the mouths of the outermost hollow grate-bar bearers, and upon the inclined sole of which the dust is precipitated to two diametrically opposite suction connections 8. These connections or nozzles 8 may also be shut off, and in this'case the suction is efiected through one or two opposite suction nozzles 8'.

Figure 7 shows hollows grate-bar bearers with lateral suction apertures 2', which have to be covered over unless they aresmaller than the size of grain of the charge.

The hollow grate-bar bearers, if a relatively stiff and fire-proof structural material is employed, such as sheet steel, cast steel, cast iron or artificial stone, may be open on the under side throughout theirlength.

The apparatus according to the invention is distinguished by great simplicity, small over-all height,-and therefore case of insertion, the open top of the furnace shaft remaining completely free. The apparatus composed of the hollow grate-bar bearers, suction passages, dust-removing connections and. ventilator connections can be mounted upon the masonry of the shaft or can be inserted in the frame structure or masonry of the shaft at any convenient height, even below the open top of thefurnace shaft.

.What I claim is:

'1. Means for drawing off Waste blast-furnace gases by suction in shaft furnaces having open tops for roasting, calcining or drying, comprising a suction grate fitted into the furnace immediately below the open top of the furnace, the said suction grate consisting of tubular hollow bearers formed with suction apertures, and the ends of the hollow bearers being open, and a, channel of large cross section surrounding the stack and in communication with the-open ends of the hollow bearers for producing an equalization of pressure on the entire circumference of 1 the furnace.

v 2. Means for drawing 01f waste blast-furnace gases by suction in shaft furnaces having open tops for roasting, calcining or drying, comprising a suction grate fitted into the furnace immediately below the open top of the furnace, the said suction grate consisting of tubular hollow bear ers, formed with suction apertures, and the ends of'the hollow bearers being open, a ventilator, an annular channel of large cross sectionsurrounding the furnace and in communication with the open ends of the bearers, and a ventilator having a suction inlet connected with the channel.

JOSEF HORAK. 

